Changes in muscle mass, muscle strength, and power but not physical function are related to testosterone dose in healthy older men

Abstract

OBJECTIVES: To examine the effect of graded doses of testosterone on physical function and muscle performance in healthy, older men. DESIGN: Randomized, double-blind, placebo-controlled clinical trial. SETTING: General clinical research center. PARTICIPANTS: Community-dwelling healthy men aged 60 to 75 (N=44). INTERVENTION: Monthly treatment with a gonadotropin-releasing hormone agonist plus 25, 50, 125, or 300 mg/wk of intramuscular injections of testosterone enanthate for 20 weeks. MEASUREMENTS: Skeletal muscle mass (SMM) was estimated using dual-energy X-ray absorptiometry. Leg press strength was measured by one repetition maximum, leg power by Nottingham Leg Rig, and muscle fatigability by repetitions to failure in the leg press exercise. Stair climbing, 6-meter and 400-meter walking speed, and a timed-up-and-go (TUG) test were used to assess physical function. RESULTS: Significant testosterone dose- and concentration-dependent increases were observed in SMM (P